This invention relates to an automotive safety belt retractor and particularly, to one having an improved comfort mechanism and a method of operating the same.
Most motor vehicles are equipped with seat and shoulder belt systems which act to restrain the occupants when the motor vehicle is subjected to high rates of deceleration which may occur, for example, during a motor vehicle collision. Many modern day safety belt retractor assemblies are of the emergency locking retractor (ELR) type. Typically, these retractors employ an inertia sensitive actuator which prevents the belt webbing from being withdrawn when the vehicle is subjected to deceleration forces above a predetermined level, thereby restraining the vehicle occupant. However, during normal operating circumstances, the belt webbing may be controllably withdrawn from the retractor for enabling increased freedom of movement by the vehicle occupants. As such, emergency locking retractors provide improved ride comfort and convenience for the occupants.
Modern safety belt retractor assemblies are also frequently equipped with a tension relief device or so-called "comfort" mechanism which prevents the retractor from constantly exerting a retracting force on the belt webbing which tends to be uncomfortable and annoying to the occupants. These systems typically sense the magnitude and direction of belt movement for triggering actuation of the comfort mechanism. Thereafter, the "slack" generated by the comfort mechanism can be cancelled by withdrawing a predetermined length of the belt from the retractor. One exemplary type of "comfort" mechanism includes a rotatable cam and follower type mechanism which allows the retractor to introduce "slack" into the belt when the vehicle is being operated.
In view of the foregoing, there is a need to provide an improved comfort mechanism for safety belt retractors which requires a conscious "intentional" and "deliberate" act by the occupant for actuating the comfort mechanism to set the belt slack. As such, the seat belt retractor of the present invention will not permit tension relief until the improved comfort mechanism is actuated with a deliberate and intentional act by the vehicle occupant.
It is therefore an object of the present invention to provide a method and apparatus for intentionally actuating a comfort mechanism of a seat belt retractor assembly.
The improved comfort mechanism in accordance with this invention achieves the above-mentioned desirable feature through the use of a follower or locking member which interacts with a driven member. A pivotable shutter device is located intermediate the follower and the driven member such that the follower is adapted to normally engage the shutter to orient the comfort mechanism in a "non-actuated" position. Therefore, tension relief is prohibited during normal protracted and retracted movement of the seat belt upon movement of the occupant in the vehicle since the shutter acts to inhibit the follower from engaging the driven member. Upon extracting the belt to its full extended position, an intentional and deliberate "tug" or "snapping" of the belt causes the shutter to pivot to an "actuated" position whereby the follower is permitted to engage the driven member for thereafter providing tension relief in a known manner.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and appended claims, taken in conjunction with the accompanying drawings.